Question 1022555
Why ask about circumference for a triangle?  Do you mean for the inscribed or circumscribed circle?  If you mean "perimeter" of the triangle, then use distance formula for the three sides and sum them.


{{{AB+BC+CA}}}
{{{sqrt((3+2)^2+(-1+1)^2)+sqrt((-2-3)^2+(-1+8)^2)+sqrt((3-3)^2+(-8+1)^2)}}}
{{{sqrt(25)+sqrt(25+49)+sqrt(49)}}}
{{{5+sqrt(74)+7}}}
{{{12+sqrt(74)}}}----------perimeter of the triangle with those three vertices.